Furnace wall



May 21, 1935. H. E. PRESTON FURNACE WALL Filed Aug. 6, 1931 2 Sheets-Sheet l May 21, 1935. H. E. REsToN FURNACE WALL 2 Sheets-Sheet 2 Filed Aug. 6, 1931 Patented May 21, 1935 FURNACE WALL Herbert E. Preston, Philadelphia, Pa., as'signorto American Engineering Company, Philadelphia, Pa., a corporation of Pennsylvania Application August 6, 1931, Serial No. 555,548

3 Claims.

This invention relates to improvements in furnace Wall structures, and while applicable in principle to various types of furnaces, has an application of particular value to the walls of Stokerfed furnaces. In stoker-fed furnaces, and particularly with stokers of the multiple under-feed type, such for example as shown in the U. S. patent of'Maxwell Alpern, No. 1,443,202, it is customary to provide, particularly in those parts more directly subjected to the higher temperatures, fluid-cooled wall sections or panels, which are better adapted than the ordinary walls to Withstand the high temperature conditions, and which have other advantages hereinafter set forth. For maximum efliciency it is desirable to maintain these fluid-cooled walls free from slag, which, normally forming on the upper portions of the wall, flow down the surface of the latter to the fuel-bed. With stokers of the abovementioned type it is of particular importance to avoid slag accretions on the lower portions of the wall immediately adjacent the fuel-bed, since such accretions interfere with a normal feeding of the fuel in the retorts; r

A principal object of my invention, therefore, is to provide novel and improved means for maintaining these or other portions ofthe walls of a furnace, and particularly of stoker-fed furnaces, free from slag accumulations.

Another object of the invention is to provide a fluid-cooled wall structure, comprising as a built-in part thereof, means for preventing accumulations of slag on the surfaces thereof.

A more specific object of the invention is to provide a wall structure having novel means for deflecting molten slag flowing down the wall from those portions thereof immediately adjacent the fuel-bed.

Still another object of the invention is to provide in a stoker furnace, means for diverting molten slag from the wall surfaces at a point above the fuel-bed directly into the retorts, whereby the said slag is carried off to' the ash-pithy normal feeding of the fuel through the stoker.

A further object of the invention is to provide a fluid-cooled panel structure forthe'walls of furnaces, comprising simple and highly effective tubes, wherein certain of said blocks constitute means for deflecting molten slag from the surface of the panel. 7

The invention further V structural details hereinafter set forth and,illustrated in the attached drawings, in which: x

Fig. 1 is a more or less diagrammatic longitudinal sectional view through thecombustion chamber of a stoker furnace, wherein the-walls. are made in accordance with my invention; Fig. 2 is a section on the line 2--2,- Fig.1; u Fig. 3 is a view in perspective of one of the elements of the wall structure shown in Fig. 2; and Fig. 4 is a fragmentary enlargement of a portion of the rear wall of the furnace shown in Fig. 1.

With reference to Fig. l of the drawings, l is the front wall, 2 the rear wall, and 3 one of the side walls of a stoker furnace. The stoker indicated at 4 is of the under-feed multiple retort type, including aninclined series of. alternately arranged retorts and tuyres, one of the retorts lying immediately adjacent each of the side walls 3. This stoker extends downwardly from the front wall I and terminates in an ash-pit 5, the fuel being introduced to the retorts through suitable openings in the front wall I and being fed during combustion downwardly through the retorts, the ash residue being deposited in the ash-pit. I

The side walls 3 areprovided in the present instance 'with a fluid-cooled panel 6, extending resides in certain novel from the front wall I to the rear wall 2,.said

panels lying immediately adjacent the sides ofthe stoker and being'inclined at an angle corresponding approximately to the inclination of the latter. These panels accordingly formside abutments for the upper portions of the fuel-bed. As illustrated in Fig. 1, the panel comprises a series or bank of tubes 1, which extend longitudinally of the panel from aheader 8 at the frontpwall to a header 9 behind the rear wall 2. The headers 8 and 9 are connected through pipes Hand l2 in a circulating fluid system. The panel further comprises a series of facing blocks l3, which are suitably secured against the inner'faces of the tubes and form the effective inner wall sur face. These blocks may be made of any suitable refractory material suchas metal, refractory clay or brick, or a combination of both. The rear wall 2 of the furnace comprises a series of upright tubes l4, corresponding to the tubes 1 of the side panel and a plurality of'facing elements l5 are secured against the sides of the tubes to form the clearly shown in Fig. 2. As therein illustrated, the said wall is provided with an elongated opening I6, which is defined bya suitable supporting frame, the panel 6 being secured at the inner end of this opening with its inner face substantially flush with the adjacent portions of the inner wall surface. The facing blocks l3 are adapted for location between adjacent tubes, being formed with curved recesses which contact a substantial portion of the outer surfaces of the tubes between which they are inserted. These blocks are drawn securely against the tubes and are held in position by studs ll, which'extend rearwardly therefrom between the tubes and through a clamp l8, which in the present in-- stance is in the form of a bar engaging the backs of the tubes of the entire series. The lower series of blocks lSa are formed to embrace the lower tube of the series and to contact the adjacent tube, the upper series of blocks I322 being similarly formed to embrace the upper tube of the seriesand to contact the next lower tube. Fluid-cooled panels of this general construction are illustrated in the application of Edward Wheeler, No. 250,237, filed January 28, 1928',

in accordance" with' my invention, I form the upper-series of -bl'oclgsl3b as illustrated in Fig. 3. This'block is of greaterthickness at its lower edge than at the upper edge, so that when secured in position against the tube the said lower end projects outwardly beyond the face of the wall as defined by the outer faces of the blocks Je ne l3a. The series of blocks i312 thus forms in effect 'aninclined ledge overhan 4 ing' the entire panel. As a consequence, molten slag flowing down the'upperportions of the 'wall on to the panel is deflected away from the surface of the latter -and drips directly into the fuel-bed. Preferably the overhang of the blocks l3b is such that th'e slag will fall directly into the stoker retorts adjacent the panels, whereby the slag will be carried downwardly with the fuel in the normal feeding operation and will eventually be discharged into the ash-pit. A characteristic of fluid-cooled panels of this type istheirtendency toprevent heavy formations of slag, nd by deflecting the molten slag flowing from the upper portions of the wall as described above, the entire panel is maintained substantially free fromslag. The efiiciency of the wall thereby remains-at a maximum. Also, slag accumulations at the lower portions of the panel which abuts the fuel-bed are substantiallyeliminated, as that there is no interference with the normal feeding of the fuel in the side retorts of the stoker. The-invention provides an' extremely simple and highly practical solution of the slag problem, particularly in connection with stoker furnaces of the type set forth, and involves no material departure in the normal construction of the wall. Substantially the same principle is employed in the rear wall 2 for maintaining the wall substantially free from slag. As illustrated in Fig. 4, certain of the transverse series of blocks i i, identified by the reference numeral lea, are formed to provide deflecting ledges from which the slag fiowing'down the wall onto the fluidcooled portion is deflected from the surface of the latter directly into the ash-pit 5. In the present instance I have shown two of the transverse series of blocks so formed and it will be apparent that still others of the facing blocks may be so formed if required.

While I have illustrated my invention as applied to the side and rear walls of astoker furnace, it will beapparent that the same principle may be employed to advantage in any furnace wall structure of this general type, either with or without the fluid-cooled feature. It will also be apparent that the structural form of the elements I31) and Ma may vary considerably without departure from the invention. Furthermore, while in the illustrated embodiment the invention is applied to a wall structure in which fluid-carrying tubes are provided throughout with facing blocks, it will be apparent that the same principle of slag diversion may be applied to walls in which the tubes are exposed for-preventing molten slag flowing onto the latter.

I. In a furnace, the combination with a fuel supporting structure, of a plurality of liquid conducting tubes provided at one side of said structure, and a plurality of rows of protective elements detachably secured against the tubes and providing a wall surface bounding the fuel bed, one of said rows of protective elements projecting inwardly from said wall surface to form a ledge overhan ing the'fuel bed whereby any slag flowing down the wallis diverted away from the Wall surface therebelow, and into. the fuel bed, and the inner surfaces of saidlast mentioned elements inclining downwardly and'inwardly.

Z. In a furnace wall, a plurality of fluid conducting tubes provided in said wall, rows of protective blocks secured to said tubes in side to side relation forming a' smooth continuous surface, one or more of said rows of blocks projecting inwardly from said wall to form an overhanging ledge whereby any slag flowing down the Wall is diverted away from the portion of the wall therebelow,.said last 'mentionedrows of blocks being spaced verticaliy and the inner surfaces thereof inclining downwardlyand'inwardiy, tube receiving recesses in the outer side of all-of said blocks, and means for clamping said blocks into intimate contact with said tubes.

3. In a furnace wall having an opening inclined to the horizontal, a protective structure substantially closing one side of said opening, said protective structure comprising a series of inclined tubes, rows of protective blocks secured to said tubes, the inner surface of said blocks being substantially flush with the inner surface of said wall forming a smooth continuous surface, one or more of saidrows of blocks projecting inwardly from said wall to form an overhanging ledge whereby any slag flowing down the wall is diverted frenrthe portion of the wall therebelow, the inner surfaces of said last mentioned blocks inclining downwardly'and inwardly, one or more tube receiving recesses provided in the outer side of all of said blocks, and means for clamping said blocks into intimate contact with said tubes.

HERBERT E. PRESTON. 

